Papers by Keyword: Trajectory Generation

Abstract: In industry, the special kind of trajectory is often designed to fit the desired motion required. In literature, four-bar mechanism is popularly applied and well studied in the trajectory generation. Different types of trajectories are generated by the choose of the ratio of links. The five-bar mechanism is another popular one to generate the desired trajectory and it is more flexible due to it has two degrees of freedom. The geared five-bar mechanism is then commonly used by reducing the degree of freedom of the mechanism into one by implied one pair of gear. In this study, the trajectories generated by a novel cam driven five-bar mechanism proposed by the authors are investigated. It could supply more choices in the application of trajectory generation.

Abstract: Hexapod walking robot is a complex electromechanical system with many degrees of freedom. Six legs ensure robot’s stability as at least three legs are always on the ground but require more effort in order to synchronize them for a successful locomotion. In this paper, we present a method that allows calculate feet trajectories in real-time and online. This method enables to select different gaits and their parameters.

Abstract: Naturalistic walking is one of the most important purposes of researches on biped robots. A feasible way is to translate the understanding of human walking to robot walking. One of the options that affects the quality of motion in a biped robot is concerned with trajectory generation. So, in this paper it's focused on trajectory generation methods for implementing a 7-links planar walker biped robot. Also, this model is simulated by VisualNastran software package and run according to a Clinical Gait Analysis (CGA) reference that has been modified for a planar model. Lastly, the results of simulation are reported.

Abstract: V-shaped surface with two planes linked by an arc surface is widely used in structure design, such as inlet duct. According to its characteristic, the transverse painting method is adopted to plan painting trajectory for its inner surface. Along the curve of the cross-section, the plane area is painted under the uniform speed of spray pattern and the arc area is painted under the uniformly accelerated and decelerated motion. The maximum speed is calculated by the transfer efficiency of the plane area and arc area. Experimental tests and evaluation are carried out on an arc-transit duct with rectangular cross-section. The results show that in this approach, the maximum positive relative deviation, maximum negative relative deviation and average relative deviation are obviously lower than those with equal painting speed on all surface.

Abstract: In the paper a trajectory generation algorithm for two robots’ coordinated motion is presented. Two instances of the algorithm, each for one robot, run in the same time and calculate trajectories’ position and orientation coordinates. Initial and end robots’ end-effectors poses are defined and values of linear and angular speeds are programmed. To minimize relative position and orientation errors an idea of corrective motion is introduced. Trajectory coordinates are calculated as the sum of programmed and corrective motion. The algorithm was implemented in a simulation environment and results of simulation are presented. Static accuracy analysis for general case and stability verification for fixed values of robots’ parameters are described. Finally, an outline of proposed procedure of building a virtual environment for reachability verification and collision checking is presented.

Abstract: A non-parallel initial state path planning algorithm for the automatic parking system is presented in this paper. Automatic parking system is a hot research point in intelligent vehicle application fields, and the trajectory generation is one of its key technologies. In the actual process of parking, the initial state of vehicle is always non-parallel to the parking place, so this situation should be researched to serve automatic parking system better. According to the analysis of vehicle kinematics model and the parking process, the trajectory can be considered as the combination of some sections of tangent arc. In this article, the trajectory is composed of several period of circular arc and it is improved by combining with the actual circumstance, then a strong adaptable parking trajectory for the automatic parking system is designed. The simulation analysis is done to verify the geometry trajectory, and the method is used on our intelligent vehicle to check out the feasibility. Compared with traditional trajectory generation method, experimental results show the adaptability and success rates of the method designed in this paper is much more better, which the parking success rates is about 90%.

Abstract: This paper presents a trajectory generation approach for a 7-DOF biped robot on level ground. Simultaneously rotation of feet in double support phase is considered which leads to high-speed and more similar to human being walking. The zero moment point (ZMP) stability criterion is used to ensure the stability of the bipedal walking robot. Since ZMP trajectory in human walking does not stay fixed, it needs to be a straight line shaped forward ZMP trajectory to have a natural walk. A genetic algorithm based method is proposed to obtain key parameters in trajectory generation such that the ZMP follows a predefined trajectory while minimizing power consumption. Simulation results demonstrate the effectiveness of the proposed method.

Abstract: In the trajectory planning process of spray painting robot, an approach to automatic trajectory generation of spray gun using point cloud slicing is presented. Firstly, the point cloud data is obtained by scanning the surface of the workpiece. After the uniform slicing of point cloud model, the spraying position is determined by the average sampling of cross-section contours. Then the normal vectors of the sampling points are estimated. Finally the trajectory of spray gun is generated by offsetting the sampling points along their normal vectors. Experimental results show that the method has good feasibility and effectiveness. The spraying trajectory, direction and distance of spray gun can be controlled accurately, thus the spraying quality and efficiency are improved.

Abstract: This work presents the problem of trajectory generation based on the use of artificial potential fields associated to articulated robotic manipulators, in order to find a trajectory so that a manipulator reaches a goal from an initial position without colliding with obstacles within its workspace. The search of a continuous sequence of collision-free configurations between an initial configuration and the final position implies the exploration of a non-linear solution space which can be described and solved with an optimization approach. It does not take into account the use of complex mathematics in an analytical or numerical solution of the inverse kinematics, where are shown manifolds solutions as a result of the angular displacements of each joint of the robot. The genetic algorithm used as strategy, reduces the complexity of the problem, because the geometric connection equations are obtained systematically. In addition, the artificial potential field simulates the attraction and repulsion forces between the goal and the obstacles, where the goal is identified as the global minimum and the obstacles as restricted points. Altogether the potential field and the genetic algorithm generate trajectories for the robot among the obstacles through the design of an appropriate fitness function that effectively drives the manipulator to the desired while avoiding collide with the obstacles.